Abstract

An optimization method for design of SPP-based metallic nanoaperture optical elements is presented. The design process is separated into two steps: Firstly, derive the amplitude and phase modulation of isolating single slit with different width; Secondly, realize the optimal design of element by using an iteration procedure. The Yang-Gu algorithm is expanded to perform this design. Three kinds of lenses which can achieve various functions have been designed by using this method. The rigorous electromagnetical theory is employed to justify and appraise the performances of the designed elements. It has been found that the designed elements can achieve the preset functions well. This method may provide a convenient avenue to optimally design metallic diffractive optical elements with subwavelength scale.

Figures (7)

SPPs lens with one focal spot designed by the Yang-Gu algorithm. (a) Objective and designed intensity distributions. (b) Distributions of the slit widths. (c) Normalized intensity distribution of |Hy| for the designed lens calculated using the FDTD method. (d) Cross section of the focal spot along the z direction.

Chromatic dispersion of the SPPs lens with one focal spot, optimally designed for λ = 650nm, but operating at different wavelength, as indicated in each plot. The dashed line indicates the real focal plane for λ = 650nm.

Lens with two focal spots designed by the Yang-Gu algorithm. (a) Objective and designed normalized intensity distributions. (b) Distribution of the slit widths. (c) Normalized intensity distribution of |Hy| for the designed lens calculated using the FDTD method. (d) Cross sections of the focal spots along the z direction.

Chromatic dispersion of the SPPs lens with two focal spots, optimally designed for λ = 650nm, but operating at different wavelengths, as indicated in each plot. The dashed line indicates the focal plane for λ = 650nm.

Lens with three focal spots designed by the Yang-Gu algorithm. (a) Objective and designed intensity distributions. (b) Distribution of the slit widths. (c) Normalized intensity distribution of |Hy| for the designed lens calculated using the FDTD method. (d) Cross sections of focal spots along the z direction.

Chromatic dispersion of the SPPs lens with three focal spots, optimally designed for λ = 650nm, but operating at different wavelength, as indicated in each plot. The dashed line indicates the real focal plane for λ = 650nm.